Knife sharpening mechanism for cutting machines



Nov. 3, 1942, f P. J. CLARKE-ML KNIFE SHABPENING MECHANISM FOR CUTTING- MACHINES A Filed May l, 1941 2 Sheets-Sheet 2 Affe/@N575 Patented Nov. 3, 1942` amsn KNEE 'SHARPENNG MECHANISM FR CUTTING MACHNES Frederick J. Clark and carl r'. Hageman, Buffalo, N. Y., assignors to Eastman Machine Company,

Bualo, N. Y.

Application May 1, 1941, Serial No. 391,354

13 Claims.

This invention relates to knife sharpening mechanisms for cutting machines, and more particularly to improvements in sharpening mechanisms for portable cutting machines of that type commonly used for cutting cloth and other sheet materials, which are moved relatively to the work in cutting the same, and have an upright, vertically reciprocating knife.

Application for United States Letters Patent, Serial No. 314,666, led January 19, 1940, by Frederick J. and Frederick G. Clark, discloses a machine of this type equipped with sharpening mechanism for the knife, comprising abrasive grinding means or elements which are power driven for performing their grinding action and are adapted to be moved up and down along the knife so as to sharpen the edge throughout its whole length. While in said machine the grinding means or elements are driven by power at high speed to effect the grinding, they are moved by hand up and down along the knife edge for sharpening the different portions thereof.

Specific objects of our invention are to provide a sharpening mechanism of the sort mentioned, with novel and practical means of simple construction for automatically moving the grinding elements or means to and fro along the knife edge; also to provide means for this purpose which are particularly applicable to sharpening mechanisms such as disclosed in the aforesaid application; also to provide an improved automatic knife sharpening mechanism for cutting machines which will be quick, efficient and reliable in operation, and will preclude uneven or unequal grinding of different portions of the knife edge; and in which the travel of the grind- 'ing `means lengthwise of the knife edge is reversed very quickly without appreciable dwell or delay so as to prevent over grinding of that portion of the knife edge adjacent to which the shown in the accompanying drawings, and the novel features of the invention are set forth in the -appended claims:

Fig. l is a fragmentary front elevation, partly in section. of a cutting machine equipped with knife sharpening mechanism embodying the invention .and showing the position of the parts when the Sharpener is not in operation.

Fig. 2 is va side elevation, partly in section thereof.

Fig. 3 is a 'front elevation, partly in section,

of the sharpening mechanism, showing the position of the parts during the travel of the grinding means downwardly along the knife edge.

Fig. 4 is a sectional plan View on line 4 4, Fig. 1.

Fig. 5 is a sectional plan view on line 5 5, Fig. 1.

The knife sharpening mechanism, as herein illustrated, is constructed substantially as disclosed in the above-identified application, eX- cept as regards the addition thereto cr inclusion therein of the means (hereinafter termed for convenience the traversing mechanism), which causes the automatic travel of the grinding elements to and fro along the knife edge. The cutting machine and its knife sharpening mechanism, except as hereinafter explained, may be constructed as illustrated in said application, or may be of other known or suitable construction.

As herein disclosed, the machine comprises the usual base l adapted to rest and be moved about upon the supporting table for theA work,

an upright standard I l, rising from the base and supporting the stationary frame l2 of an electric motor which reciprocates the knife I3 in a guide slot in the front of the standard by means of suitable drive connections `including a crank wheel i4 on the .front end of the horizontal rotor shaft of the motor. The knife grinding elements or means, as illustrated in the drawings, comprises narrow, iiexible belts or bands l5 and IS having abrasive grinding surfaces arranged for grinding contact with opposite sides ofthe edge portion of the knife, said bands being driven from the knife operating motor, so that the stretches of the bands which Contact with the knife travel horizontally past the latter, and the bands are mounted on a carriage l1 arranged to move up and down lengthwise of the knife so as to enable the sharpening of the knife edgeV the plane thereof, to rotate and slide axially in f suitable bearings on a cover-piece or housing 22, which is stationarily but removably secured in place at the front of the machine and serves to cover the crank wheel and other parts of the knife operating mechanism. The lower portions of these shafts extend below the housing and are journalled and held from axial movement in suitable bearings on the grinder carriage .i1 so x i that the shafts will move up and dow-n with the l carriage. Pulleys 23 and 24, fixed on the lower ends of the shafts, serve to support the front ends of and drive the grinding bands. Said shafts are rotated in opposite directions by drive gearing, including three intermeshing pinions 25, 26 and 21, which are held from endwise movement in a chamber 23 in the lower portion of the housing, the shafts 2i) and 2| being connected to rotate with but slide axially through the pinions and 26, as by keys projecting from the pinions into longitudinal keyways in the shafts. The third pinion 21 may be similarly splined on the lower portion of a third or driving shaft 25 to rotate therewith but permit axial movement of the shaft through the pinion. This shaft 29 is journalled in suitable bearings in the housing 22, and may be parallel with and at one side of the two shafts 2i) and 2I. At its upper end, the shaft 29 is geared, as by intermeshing, spiral toothed pinions 30 and 3| to a horizontal shaft 32 on which is fixed a wheel 33 arranged to be driven by a crank wheel' I4. The shaft 32 and pinions 30 and 3l are suitably mounted in a gear casing 34 arranged above the housing 22 to move vertically toward and from the same, as on guide posts 35 fixed to and rising from the housing. G ear casing 34 is pressed downwardly to releasably hold the wheel 33 in driving engagement with the crank wheel I4, as by springs 35 surrounding the posts between the gear casing and nuts or heads at the upper end of the guide posts. The wheel 33 may be driven by frictional engagement with the crank wheel.

Normally, when the sharpening mechanism is not being used, the grinder carriage I1 is held in an inoperative upper position adjacent the lower end of the housing 22, as hereinafter explained, and, as by upward pressure against the lower end of the driving shaft 29, holds the gear casing 34 up with the driving wheel 33 out of driving connection with the crank wheel I4, so that,Y the grinding elements are not driven but remain stationary. Whenv it is desired to sharpen the knife, the grinder carriage I1 is lowered, as will be explained, causing wheel 33 to engage crank wheel I4 and drive the grinding elements,

kand the grinder carriage to be moved downwarcll'y and upwardly along the knife.

Reference may be had to the above-identified application for a more detailed description of the construction and operation of the sharpening mechanism.

The traversing mechanism for moving the narrow grinding elements up and down lengthwise of the knife edge for sharpening it throughout its length is preferably constructed as follows:

4U represents a vertical rack bar or toothed rack which is fixed at its lower end, as by screws 4I, to the grinder carriage I1, extends upwardly therefrom and is adapted to slide vertically in suitable guideways 42 and 43 on the housing 22. The rack has teeth, preferably along one side face, with which are adapted to mesh, one or the other 'of two oppositely driven pinions 44 and mounted on a carrier which is movable for alternately shifting one pinion into and the other pinion out of mesh with the rack. When one pinion, as 44 engages the rack teeth, the rack and the attached grinder carriage will be moved upwardly, whereasA lwhen the other pinion 45 engages the rack teeth, the rack and carriage `will be moved downwardly.

As shown, these pinions are suitably journalled Y on a rocking carrier 48, preferably of U-shape,

`rack and grinder carriage up.

with the pinions arranged between the legs thereof, on shafts 41 and 48 bearing in holes in the opposite legs of the carrier 46. The carrier rocks about a pivotal axis between the axes of the pinions 44 and 45 to move one pinion into mesh with the rack as the other is moved out of mesh therewith. The pinions intermesh so that by driving one, the two pinions will rotate in opposite directions. Preferably, the pinions are driven by a pinion 49 fixed to shaft 48 of pinion 44, and meshing with a driving pinion 50 arranged at one side of the carrier 45 in axial alinement with the pivotal axis of the carrier. As shown, the driving pinion 59 is fixed on a shaft 5I which is journalled to rotate in a bushing 52 in a bearing 53 on the housing 22. The inner end of shaft 5I projects into a hole in the adjacent leg of the carrier 46 and cooperates with a coaxially arranged stud shaft 54 fixed in a bearing bracket 55 on the housing 22 and projecting into a hole in the opposite leg of the carrier to form the pivotal mounting for the carrier. l

Fixed on the shaft 5I, to which the driving pinion 50 is Xed, is a worm wheel 56 which meshes with and is driven by a worm 51 on the vertical driving shaft 29 so that when this shaft is driven, the rack pinions 44, 45 will be driven in opposite directions, and the rack will be moved upwardly or downwardly, depending upon which of these rack pinions meshes with the rack.

The rocking carrier for the rack pinions 44, 45 is shifted for placing one or the other pinion in mesh with the rack to effect travel of the rack and grinder carriage, by an operating device, preferably consisting of a pivoted lever 50 having a forked arm 62 straddling a pin 63 projecting from one end of the carrier 43. As shown, the operating lever is fulcrumed by a pivot 5I on a post projecting from the `housing 22 within a cover G4, which may be a part of or formed by a separate cover-piece secured to the housing 22, and covers the traversing gearing. The other arm of the operating lever 65 projects out through a suitable opening in one side of the cover 64 and may be provided with a finger-piece or handle 65 at its outer end for actuating the lever.

Normally, when the knife sharpening means are out of action, or stationary, the operating lever is releasably'held by a suitable spring 66 in the position shown in Fig. l, in which rack pinion 44 meshes with the rack 40 and holds the Spring 66, as shown, is a compression coil spring surrounding a rod 61 and bearing at its ends against a shoulder on said rod and against a stud 68 projecting from the housing 22. one end to a stud 69 on the lever 6ft and at its other end is adapted to slide endwise in a hole in the stud 68, with the rod either adapted to rock in said hole or said stud adapted to pivot to enable the rod 61 to swing with the operating lever when the latter is actuated. When the lever is moved to shift the rack pinions, pivot stud 69 on the lever willIpass from a position at one side of a dead center line extending through the centers of the lever fulcrum 5I and fixed stud 68 to a position at the opposite side of said dead center line. Thus, the spring will act to quickly shift or snap the operating lever to and releasably hold it either in the position shown in Fig. 1, in which the rack pinion 44 meshes with the rack, or in the other position The rod 61 is pivoted at shown in Fig. 3, in which the other rack pinion 45 meshes with the rack.

It will be noted that pin $3` on 'the pinion carrier is of smaller diameter than the width of the slet in the forked arm of the operating lever, so as to permit some lost motion or play of the pin in the slot. Thus, when actuating the operating lever for shifting the rack pinions, the lever is permitted an initial movement before its forked arm engages the pin 63 and starts to move the carrier. This lost motion connection between the operating lever and the pinion carrier, together with the snap action of the lever actuating spring 68 effects a practically instantaneous disengagement of one pinion from and engagement of the other pinion withL the rack, so that there will be practically no dwell or time interval between the travel of the rack in one direction by one pinion and the reverse travel of the rack by the other pinion.

The operation of the sharpening mechanism may be described as follows: assuming the parts to be in the inactive position shown in Fig; 1, with the grinder carriage in its uppermost position and holding the friction wheel 33 up off of the driving crank wheel M, and the lower rack pinion il in mesh with the rack and holding the carriage up; if the operating lever 6i) is raised, the pinion carrier will swing lower pinion 44 free from the rack, thus permitting the rack 120 to lower the carriage and wheel 33 to engage knife, and the grinding means are thrown out of action after this single down and up movement to prevent undue grinding of the knife.

` Furthermore, the described snap action reversing the driving crank wheel I4 and the upper rack pinion 45 will be placed in mesh with the rack. The grinding means or elements will be thus set in motion for sharpening the knife provided the 1 motor has been switched on or is running. Also, the drive shaft 29 for the grinding` means, through the described worm and gearing, rotates the rack pinions M, 45 in directions such that the upper pinion 55, which then meshes with the rack, will move the rack and grinder carriage downwardly. As the carriage approaches the intended limit of its downward movement, a trip projection i@ on the upper end of the rack will strike and depress the long arm of the operating lever 69, whereupon the lever actuating spring will act to quickly snap or throw the upper pinion l5 out of mesh with the rack and the lower pinion d into mesh with the rack and thus cause the reverse or upward movement of the 34 to disengage the friction' wheel 33 from the driving crank wheel lf3, thereby stopping the rotation of the shaft 2S. IThis stops the grinding elements or means and also arrests the traversing mechanism which causes the travel of the grinding means lengthwise of the knife edge, leaving the parts inactive in the position shown in Fig. 1, with the lower rack pinion 44 in mesh with and holding the rack upwardly and the mechanism ready to be again actuated by lever Se for starting the sharpening mechanism, when it .is again necessary to sharpen the knife.

It will be noted that in the operation of the sharpening mechanism as disclosed herein, the grinding means or elements travel first downwardly along the knife edge and then upwardly,

and the motion of the driving and traversing mechanism for the grinding means is arrested when the grinder carriage is returned to its upper position, shown in Fig. 1, after one downward movement, so that the grinding means are thrown means operates to effect the reversal of travel of the-grinder carriage very quickly when it has reached the limit of its downward travell prevents a dwell or arrested motion of the grinder carriage between its downward and upward movements which, if permitted to occur, would result in grinding the lower end of the knife edge to a greater extent than other. portions thereof, with the result that a concaved edge would be ground in the lower end portion ofthe knife. Should the knife be so dull that itis necessary to cause the grinding means to travel downwardly and upwardly more than once, vto produce the required keen edge on the knife, the downward and upward motions of the grinding means can be repeated by successive operations of the operating lever Si), but in the ordinary use of the machine, the sharpening mechanism is thrown oui-.of action after the grinder carriage has travelled once downwardly and upwardly along the knife edge. The described automatic traversing mechanism is exceedingly simple and adds but few parts to a, sharpening mechanism such as shown in said pending application, in which the grinding means are moved by hand lengthwise along the knife edge; and by the use of the rack secured to thegrinder carriage and sliding in guides: on the stationary machine frame, on which the rack-operating gearing is mounted, a very sturdy, reliable and durable automatic Sharpener is provided.

In the sharpening mechanism as herein disclosed, the knife is sharpened by flexible .grinding belts and the front sup-porting and driving pulleys 2?.- and Eil, for these belts are fixed directly to the lower ends of theshafts 2li and 2|, both of which slide with the grinder carriage in the up and down travel thereof, lengthwise of the knife edge. This construction makes an ',efiicient and desirable sharpening mechanism in which the two shafts cooperate in guiding the carriage up and down and preventing twisting or lateral motion of the same. It will be understood, however, that this invention is not restrict-ed to sharpening mechanisms employing flexible band grinding means, but that grinding means or elements of other kkinds could be ernployed and operated hy the driving mechanism disclosed, and also that the improvements are not confined in. application to ay construction in which the grinding elements are directly connectedto or supported by two sliding shafts, such as 20 and ZI, since band grinding means, such as shown, or other grinding elements, could be operated, for example, by a single, vertically .movable shaft geared to the grinding elements, as disclosed in U. S. Patent No.2.l83,787, issued December 19, 1939, to Frederick J. Clark, assignor to Eastman Machine Company.

We claim:

l. in a knife sharpening mechanism for cutting machines comp-rising knife grinding means, drive mechanism therefor, and a carriage for said grinding means arranged'to travel lengthwise of the knife edge for presenting the grinding means to diiferentportionsof the edge, trav- This tlie carriage to and fro along thev knife edge,

`comprising a toothed rack connected to travel with said carriage, oppositely driven pinions interchangeably engageable with said rack, an operating device operable to engage one pinion with said rack to cause said rack to travel in one direction, and a trip device constructed and arranged to actuate said operating device for dis- .engaging said pinion from and engaging the other pinion with the rack to reverse the direction of vtravel of the rack.

2. A knife sharpening mechanism as set forth in claim 1, in which said trip device is movable Fwith said rack for actuating said operating device.

v3. In a knife sharpening mechanism for cutting machines comprising a stationary frame,

:knife grinding means, drive mechanism therefor, and a carriage for said grinding means arranged to travel lengthwise of the knife edge for presenting the grinding means to different por- 'tions of the edge, traversing mechanism for ef- .fecting such travel of the carriage to and fro :and arranged to actuate said operating device- Ifor disengaging said pinion from and engaging the other pinion with the rack to reverse the direction of travel of the rack.

4. In a knife sharpening mechanism for cutting machines comprising knife grinding means,

-drive mechanism therefor, and a carriage for said grinding means arranged to travel lengthwise of the knife edge for presenting the grinding means to different portions of the edge, traversing mechanism for effecting such travel of the carriage to and fro along the knife edge, comprising. a toothed rack connected to travel vwith said carriage, oppositely driven pinions, a

carrier for said pinions past which said rack travels and which is movable for interchangeably engaging said pinions with the rack, an

operating device for shifting said carrier to en- 'i gage one pinion with said rack to cause the rack .to travel in one direction, and a trip device constructed and arranged to actuate said pinion carrier for disengaging said pinion from and engaging the other pinion with the rack to reverse the ldirection of travel of the rack.

5. In a knife sharpening mechanism for cutvting machines comprising knife grinding means,

drive mechanism therefor, and a carriage for said grinding means arranged to travel lengthwise of the knife edge for presenting the grinding means to different portions of the edge, traversing mechanism for effecting such travel of the carriage to and fro along the knife edge, comprising a toothed rack connected to travel with said carriage, oppositely driven pinions interchangeably engageable with said rack, an operating device operable to engage one pinion with said rack to cause said rack to travel in one direction, a trip device constructed and arranged to actuate said operating device for dsengaging said pinion from and engaging the other pinionl with the rack to reverse the direction of travel of the rack, and means constructed and arranged to stop said sharpening mechanism at the end of v ersing mechanism for effecting such travel of the rst reverse travel of the rack and carriage.

6. In a knife sharpening mechanism for cutting machines comprising knife grinding means,

drive mechanism therefor, and a carriage for` said grinding means arranged to travel length- Wise of the knife edge for presenting the grind- Ving means to different portions of the edge, traversing mechanism for effecting such travel of the carriage to and fro along the knife edge, comprising a toothed rack connected to travel with said carriage, oppositely driven pinions interchangeably engageable with said rack, an operating device operable to engage one pinion with said rack to cause said rack to travel in one direction, a trip device constructed and arranged to actuate said operating device for disengaging said pinion from and engaging the other pinion with the rack to reverse the direction of travel of the rack, and means actuated by said carriage to stop said sharpening mechanism at the end of the rst reverse travel of the rack and carriage.

'7. In va knife sharpening mechanism for cutting machines comprising knife grinding means, drive mechanism therefor, and a carriage for said grinding means arranged to travel lengthwise of the knife edge for presenting the grinding means t0 different portions of the edge, trav- `ersing mechanism for eiecting such travel of the carriage to and fro along the knife edge, comprising a toothed rack connected to travel with said carriage, a pair of pinions interchangeably engageable with said rack, worm gearing for driving said pinions in opposite directions, an operating device operable to engage one pinion with said rack to cause said rack to travel in one direction, and a trip device constructed and arranged 4to actuate said operating device for dis- 'engaging said pinion from and engaging the other pinion with the rack to reverse the direction of travel of the rack.

8. In a knife sharpening mechanism for cutting machines comprising knife grinding means, drive mechanism therefor, and a carriage for said grinding means arranged to travel lengthwise of the knife edge Ifor presenting the grinding means to different portions of the edge, traversing mechanism for effecting such travel of the carriage to and fro along the knife edge, comprising a toothed rack connected to travel with said carriage, a .pair of pinions interchangeably engageable with said rack, worm gearing for driving said pinions in oppositedireotions, an operating device operable to engage one pinion with said rack for c-aus-ing the rack to travel in o-ne direction, a trip device constructed and arranged to actuafte said operating device for -disengagng said pinion from and engaging the other pinion with the rack to reverse the direction of travel of the rack, and means constructed and arranged to throw said shanpening mechanism out of action at the end of the first reverse travel of the rack and carriage.

9. A knife sharpening mechanism as set forth in claim 1, in which a snap action spring device is incorporated constructed and arranged to snap said pinions quickly into and out of engagement with the rack.

10. IA knife sharpening mechanism as set forth `in claim l, in which said operating device has a lost motion actuating connection with said pinions, and a spring device is arranged to be strained during the lost motion travel of said olperating device and to act at the end of said lost motion travel to snap said pinions quickly int-o and out of engagement with the rack.

l1. -In a knife sharpening mechanism for cutting machines 4comprising a stationary frame, knife grinding means, drive mechanism therefor, and a carriage for said grinding means arranged to travel lengthwise of the knife edge for presenting the grinding means to different portions of the edge, traversing mechanism for eiecting such travel of the carriage to and fro along the knife edge comprising a bar extending approximately parallel with the knife edge land connected to and mova'ble with said carriage, oppositely driven pinions shiftably mounted on said stationary frame for interchangeable propelling engagement with said bar, means for eng-aging one of said pinions with said bar for eieoting travel of said bar and carriage in one direction, and trip mechanism actuated by the carriage and constructed and arranged to shift said pinions and engage the other pinion with said bar at the end of its travel in said one Vdirection to eect reverse travel of the bar and carriage.

12. A knife sharpening mechanism as set forth in claim 11, in which a snap-action spring device is incorporated constructed and arranged to quickly shift said pinions into and out of propelling engagement .with said bar.

13. In knife sharpening mechanism for cutting machines comprising knife grinding means, drive mechanism therefor, and a carriage for said grinding means arranged to travel lengthwise of the knife edge for presenting the grinding means to different portions of the edge, traversing mechanism for effecting such travel of the carriage to and fro along the knife edge, comprising a toothed rack connected to travel with said carriage, oppcsitely driven pinions interchangeably engageable with said rack, an operating device operable to engage one pinion With said rack to cause said carriage to travel in oneidirection from an initial position, a trip device controlled by the movement of the carriage and constructed and arranged for disengaging said pinion from and engaging the other pinion with the rack to reverse the direction of travel of the rack, and means controlled by Imovement of the carriage and constructed and arranged to stop said sharpening mechanism when said Icarriage has been returned to its initial position.

FREDERICK J. CLARK. CARL F. HILGEMAN. 

